Federal Air Quality Management System

The federal Air Quality Management System is a collaborative approach for reducing air pollution in Canada. It consists of several elements:

• Canadian Ambient Air Quality Standards (non-regulatory health and environmental-based air quality objectives intended to drive improvements where needed)
• air zones (management areas delineated within a province or territory)
• regional airsheds - transboundary air pollution (broad geographic areas that encompass a number of air zones and may cross provincial/territorial and international boundaries)
• base-level industrial emissions requirements
• mobile emission sources (transportation)

Air zones – Managing air quality in Ontario

Ontario has identified three air zone categories under the federal Air Quality Management System based on factors such as pollutant sources, topography, meteorological patterns, population density and other potential factors that influence ambient air concentrations.

This has resulted in six air zone areas for the province as presented in the table below.

Ontario has designated specific ambient air quality monitoring stations as CAAQS reporting stations for each of the identified air zones in the province. Designated sites normally refer to communities with populations greater than 100,000 and/or communities with large industrial sources.

Canadian Ambient Air Quality Standard achievement

10-year trends – Fine particulate matter

10-year trend of 24-hour PM_2.5 CAAQS metrics in Ontario

This is a line graph showing the trend of the 24-hour fine particulate matter Canadian Ambient Air Quality Standard metrics from 2010 to 2019 in Ontario. This trend shows Ontario’s decrease of 21% over this 10-year period. To view the data for a specific location, please select the 'Stations' radio button and use the drop-down menu.

Note:

• The Ontario 10-year trend is based on data from 23 ambient air monitoring stations.
• The CAAQS for 24h PM_2.5 (28 µg/m³) is based on the 98th percentile measurement annually, averaged over three consecutive years.

10-year trend of annual PM_2.5 CAAQS metrics in Ontario

This is a line graph showing the trend of the annual fine particulate matter Canadian Ambient Air Quality Standard metrics from 2010 to 2019 in Ontario. There was no significant trend for Ontario over this 10-year period. To view the data for a specific location, please select the 'Stations' radio button and use the drop-down menu.

Note:

• The Ontario 10-year trend is based on data from 23 ambient air monitoring stations.
• The CAAQS for annual PM_2.5 (10 µg/m³) is based on the annual mean averaged over three consecutive years.

The 10-year trends, based on the 24-hour and annual PM_2.5 CAAQS metrics at each of the designated monitoring sites, are presented in Appendix: PM_2.5 and ozone CAAQS metric trends for designated sites across Ontario (2010-2019).

2019 results – Fine particulate matter

PM_2.5 CAAQS metric values for designated sites across Ontario, 2019

This map displays the fine particulate matter Canadian Ambient Air Quality Standard metric values for designated reporting sites across Ontario for 2019 based on a 3-year average. Select the 24-hour metric or the annual metric from the drop-down menu list.

Note:

• The CAAQS for 24-hour PM_2.5 (28 µg/m³) is based on the 98th percentile measurement annually, averaged over three consecutive years.
• The CAAQS for annual PM_2.5 (10 µg/m³) is based on the annual mean averaged over three consecutive years.

A summary of the 2019 CAAQS metric values for the 24-hour and annual PM_2.5 at individual CAAQS reporting stations is in the Appendix: PM_2.5 and ozone CAAQS metric values for designated sites across Ontario (2019).

10-year trends – Ground-level ozone

10-year trend of 8-hour O₃ CAAQS metrics in Ontario

This is a line graph showing the trend of the 8-hour ozone Canadian Ambient Air Quality Standard metrics from 2010 to 2019 in Ontario. This trend shows Ontario’s decrease of 8% over this 10-year period. Select another location from the drop-down menu to learn the percent change in air quality for other communities.

Note:

• The Ontario 10-year trend is based on data from 23 ambient air monitoring stations.
• The CAAQS for ozone (63 ppb) is based on the consecutive three-year average of the annual 4^th highest daily maximum eight-hour running average.

The 10-year trends, based on the 8-hour ozone CAAQS metrics at each of the designated monitoring sites, are presented in Appendix: PM_2.5 and ozone CAAQS metric trends for designated sites across Ontario (2010-2019).

2019 results – Ground-level ozone

Transboundary influences, from both the U.S. and beyond, account for a significant portion of Ontario’s ozone when their levels are elevated. Ontario’s CAAQS reporting stations would have met the ozone CAAQS if transboundary flow days were excluded from the calculated metric using a weight of evidence (WOE) analysis.

Ozone CAAQS metric values for designated sites across Ontario, 2019

This map displays the 8-hour ozone Canadian Ambient Air Quality Standard metric values for designated reporting sites across Ontario for 2019 based on a 3-year average.

Note:

• The CAAQS for ozone (63 ppb) is based on the consecutive three-year average of the annual 4^th highest daily maximum eight-hour running average.

A summary of the 2019 CAAQS metric values for 8-hour ozone at individual CAAQS reporting stations is in the Appendix: PM_2.5 and ozone CAAQS metric values for designated sites across Ontario (2019).

Weight of Evidence (WOE) analysis

Transboundary influences, from both the U.S. and beyond, account for a significant portion of Ontario’s ozone when their levels are elevated. A Weight of Evidence (WOE) analysis demonstrates the influence of transboundary flow on days with elevated ozone concentrations and confirms that Ontario’s CAAQS reporting stations would have met the ozone CAAQS if transboundary flow days were excluded from the calculated metric.

The WOE approach consists of performing, evaluating and documenting a series of technical analyses that collectively support the conclusion that exceedances of the CAAQS on a given day were influenced by transboundary flows or exceptional events. These analyses may include assessing the meteorological conditions (airflow, wind speed and direction, temperature, stability, etc.) and pollutant concentrations in Ontario and upwind locations.

Canadian Ambient Air Quality Standards

The Canadian Council of Ministers of the Environment have developed Canadian Ambient Air Quality Standards (CAAQS) as a key element of the Air Quality Management System to drive improvement of air quality across Canada. CAAQS are non-regulatory health and environmentally based ambient air objectives that are used to assess general air quality and reflect desirable concentrations of contaminants in air from all sources. CAAQS have been developed for ozone, fine particulate matter, sulphur dioxide and nitrogen dioxide however only the CAAQS for ozone and fine particulate matter were in effect in 2019.

Source: Canadian Council of Ministers of the Environment